An increase in the anthropogenic activities leading to environmental pollution has gained awareness worldwide. The pertinacious nature of heavy metals lead to adverse health effects towards the life of both plants and animals, further resulting in crucial diseases in humans. Bioremediation is considered one of the safer, cleaner, cost effective and environmentally sound technique for removal of contamination from such sites which are contaminated with extensive range of pollutants. Heavy metals are imperishable and can only be altered from one oxidation state to another. Natures innate recycling mechanism involves certains microorganisms, which have the potential to biotransform toxic metals into a lesser toxic form which is utilized as their energy source. Reducing the toxicity of soil and water contaminants, microorganisms including certain bacteria and fungi, also play a pivotal role in promoting growth of plants in contaminated sites. Certain plant growth promoting rhizomicrobes (PGPR) including bacillus, pseudomonads, mycobacterium etc., help in increased nutrient uptake, along with higher phosphate and nitrogen content of the plants. These rhizobacteria may also lead to metal mobilization and increase metal uptake by some plant species leading to microbe assisted phytoremediation of an environmentally polluted site. The present study highlights certain bioremediation mechanisms of microbes and their role in phytobial cleaning of the environment.
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... The defence response of microbes against heavy metals is a complex process that depends on the concentration and availability of metal ions and various factors such as type of metal, medium, microbial species and facilitation type (active or passive) (Tak et al. 2013). Various other factors such as polysaccharides, proteins, lipids, receptors and functional groups (carboxyl, amido, amino, hydroxyl, etc.) are also involved during binding action of different metal ions onto microbial surfaces (Roychowdhury et al. 2019). This process of bioremediation can be carried out in situ or ex situ in soil, wastewaters, sludge and sediments. ...
... Bioattenuation is defined as the in situ technology for microbial remediation of heavy metal ions that utilises the ongoing natural processes for decontaminating the pollutants from chemical spills followed by reducing their levels at polluted sites (Emenike et al. 2018). Subsequently, the pollutants remain undisturbed at the site, for acquiring opportunity for its natural breakdown, reduction or conversion into the less toxic forms (Tyagi et al. 2011;Roychowdhury et al. 2019). The natural attenuation is closely related to site clean-up which also removes the sources of contaminants along with the contaminant itself. ...
Aluminum (Al) is the third most abundant metal in the earth’s crust after oxygen and silicone. Geologically Al has existed as a complex compound with oxygen and carbon. In addition to natural Al in the soil, in the last century Al is used in various types of industrial products giving rise to excessive accumulation in the soil. When soil pH decreases under 5, complex Al dissolves into phytotoxic forms. Al³⁺, which is the most phytotoxic form, is absorbed by plant roots and has adverse effects on plant growth and development. Al toxicity is an important agricultural problem causing dramatic yield decrease and has been substantially investigated in plant systems. The mechanisms of Al toxicity and tolerance in plants have been described as morphological, physiological, and molecular perspectives; however, it has not yet been fully elucidated because of its complex chemistry.
... We all are well aware of the fact that there is an existing issue of heavy metal contamination all over the globe and it is a serious threat to the environment as well as to living organisms. Roychowdhury et al. (2019) in their review categorized various toxic metals into various categories based on toxicity (Table 2.5). ...
The heightened increase in pollutants in the environment including soil due to the addition of different toxic chemical compounds resulting from geogenic and various anthropogenic activities is a worldwide concern. There have been a number of evidences regarding involvement of bacterial enzymes in soil bioremediation of these toxic pollutants but little work has been accomplished regarding potential fungal enzymes. In this context, development of bioremediation techniques with filamentous fungi and their oxidative enzymatic activities could be of great potent to reduce toxicity of soil pollutants namely polyaromatic hydrocarbons (PAHs), halogenated compounds, polyphenols, heavy metals, etc. Although, bioremediation through enzymatic activities of fungi is a cost-effective and eco-friendly technology, and many studies have already been performed using fungal cultures, but its study has been restricted. Therefore, more work needs to be done in this field for a commercial breakthrough regarding the use of fungal enzymes in soil bioremediation. A variety of lignolytic and filamentous fungi have been studied to perform the function employing their capability to transform or degrade specific contaminants using their enzymatic activities.KeywordsFungal enzymesHeavy metalsPAHLignolytic fungiFilamentous fungi
... We all are well aware of the fact that there is an existing issue of heavy metal contamination all over the globe and it is a serious threat to the environment as well as to living organisms. Roychowdhury et al. (2019) in their review categorized various toxic metals into various categories based on toxicity (Table 2.5). ...
Soil pollution is a major and growing concern all over the globe and a serious threat to the environment as well as to living organisms. Different pollutants, viz. heavy metals, radionuclides, organic pollutants, plastics, agrochemicals like pesticides, herbicides, etc. are known to pollute the soil and reduce the already limited arable land important for food production. In search of economical and eco-friendly remediation techniques many methodologies have been devised, such as rhizoremediation and phytoremediation, and by using them polluted lands can be put back in cultivation or other types of production systems without harming the environment any further. Bioremediation is one such technique in which microorganisms are employed for the purpose directly or indirectly. Bioremediation means the use of biological agents to detoxify and degrade environmental contaminants. Using microorganisms for remediation reduces time and labor by a variety of mechanisms. They help in bioremediation via various mechanisms such as biosorption, EPS production, metalloproteins, metal resistant genes, SOD, POD, Catalase production, volatilization, and siderophore production. Some of the microbial strains used for bioremediation are Pseudomonas, Rhizobium, Klebsiella, Bacillus, Enterobacter, and others. Microbial inoculation decreases the MDA (malondialdehyde) and H2O2 content by 20% and 33%, respectively. They also increase the antioxidant enzymes such as SOD (superoxide dismutase enzyme) and catalase by 30% and 7%, respectively. They can also biotransform the oxidation states of toxic metals to nontoxic ones. They even enhance the hyperaccumulator capacity to aid phytoremediation.
... They are the serious threats to the environment as well as to health due to their toxicity, nonbiodegradability, and bioaccumulation (Niharika et al., 2019;Ojha et al., 2013;Sharma et al., 2014). Contamination of soil and water results in a loss of biodiversity as well as the functionality of soil and water such as the nutrient cycle, and the presence of heavy metals inhibits microbial activity (Roychowdhury et al., 2019). The extensive use of pesticides has created issues not only with the environment and health but also with biodiversity Vats and Miglani, 2011;Vats et al., 2013aVats et al., , 2013b. ...
Human activities have become the source of myriad pollutants and have accelerated the pressure on natural resource depletion. Intensive farming, urbanization, rapid industrialization, and other human activities have resulted in land deterioration and degradation, a polluted environment, and a downturn in crop productivity across various sectors of agriculture. Several alternative methods have been designed and developed, but often, these processes risk environmental damage by producing secondary pollutants. Biological treatment systems have diversified applications, such as the cleanup of site contaminants in soil, water, streams, and sludge. Bioremediation, an efficacious and lucrative eco-friendly management tool, utilizes microorganisms to degrade or reduce the concentration of hazardous wastes at the contaminated site without causing additional deterioration of the environment. This chapter discusses the role of a vast array of microorganisms used in the reclamation of wastewater containing metal pollutants through bioremediation and puts forward thoughts and opportunities for further research in the field.
... They are the serious threats to the environment as well as to health due to their toxicity, nonbiodegradability, and bioaccumulation (Niharika et al., 2019;Ojha et al., 2013;Sharma et al., 2014). Contamination of soil and water results in a loss of biodiversity as well as the functionality of soil and water such as the nutrient cycle, and the presence of heavy metals inhibits microbial activity (Roychowdhury et al., 2019). The extensive use of pesticides has created issues not only with the environment and health but also with biodiversity Vats and Miglani, 2011;Vats et al., 2013aVats et al., , 2013b. ...
Bioremediation is an option to transform toxic heavy
metals into a less harmful state using microbes or their enzymes and is an ecofriendly,
cost-effective technique for revitalizing wastewater-polluted environments
Recent years’ rapid industrialization has led to the creation of new or emerging pollutants (EPs) and their release into the environment, which are thought to pose potential risks to the environment and public health. New technologies are therefore needed to decontaminate these emerging contaminants from contaminated sites. The use of living organisms (plants and microbes) in bioremediation, which has shown great promise, is time-consuming and suffers when contaminants are high (causing toxicity to the microorganisms). Recent developments in nanotechnology and bioremediation have greatly increased the potential for efficient and sustainable decontamination methods. For instance, when combined with plants, nanozerovalent iron (nZVI) rapidly breaks down organic pollutants like chlorpyrifos and can accumulate broken-down by-products. Similar to this, enzyme-loaded nanomaterials could be used to break down resistant organic pollutants into simpler compounds through the combined efforts of microbes or plants. The bioremediation technologies for treating emerging contaminants are covered in this chapter. Additionally, it discusses the integration of nanotechnology with bioaugmentation and its potential benefits and drawbacks.
Abandoned mines are environmental liabilities with a high potential for contamination of rivers, soils, and entire ecosystems, which constitutes a threat to wildlife, flora, and fauna, in addition to socio-environmental, economic, and human health risks. The objective of this study was to determine the degree of contamination of 5 abandoned mines to evaluate their potential environmental and social impact. The presence and concentration of arsenic, barium, cadmium, lead, chromium, mercury, and free cyanide by mass spectrometry, and hexavalent chromium by ion chromatography. The environmental indices of geoaccumulation, contamination factor, and contamination load were used to evaluate the level of contamination for each area. The results showed high contamination with a high content of arsenic (2,046 mg Kg − 1 ), cadmium (650 mg Kg − 1 ), lead (26,131 mg Kg − 1 ), free cyanide (92 mg Kg − 1 ), mercury (26.4 mg Kg − 1 ) above the established maximum limits, not detecting the presence of hexavalent chromium (0.03 mg Kg − 1 ). In Peru, there are many abandoned mines, so it is a latent danger of an environmental disaster. Therefore, it is essential to assess heavy metal contamination together with environmental risks, to establish efficient mitigation measures.
In recent years, rapid industrialization had led the occurrence of new or emerging pollutants (EPs) and their release to the environment that are considered to be as potential threats to environment and human health. Hence, there is a need for new technologies for decontamination of these newly emerging contaminants in contaminated sites. Biological methods such as bioremediation which involves living organisms (microbes and plants) have shown great potential, but require long time and also suffer when the contaminant level is high (causing toxicity to the microorganisms). In recent times, the advancement of nanotechnology and its integration with bioremediation provides immense potential for sustainable and effective decontamination technology. For instance, nano zerovalent iron (nZVI) rapidly degrade organic pollutants such as chlorpyrifos and coupled with plants can accumulate degraded products. Similarly, nanomaterials encapsulated enzymes might be used for the resistant organic pollutant degradation into simpler compounds due to joint activities of microbes or plants with the enzyme loaded in nanomaterial. This chapter discusses the integration of the use of nanotechnology with Bioaugmentation, its potential opportunities, and finally challenges associated with it.
The use of pesticides on a large scale globally has caused serious problems for the health of humans, animals, and the environment. Biodegradation and bioremediation of pesticides offer a much-needed solution to tackle this menace. The involvement of pesticides in the food chain has caused serious disturbances. Bioremediation and biodegradation are methods that involve creating a biological solution to mitigate, reduce, or clean xenobiotic, recalcitrant, and toxic materials from soil, water, and sediments. Various chemical and physical methods involve the use of chemicals for decontamination of soil and water, whereas physical methods such as incineration or burial are used for remediation. Bioremediation involves the use of plants (phytoremediation), microbes (microbial remediation), and animals (zooremediation), and biodegradation involves the use of microbes. Both ex situ and in situ strategies are used depending on the requirement. This chapter focuses on the most appropriate biodegradation and bioremediation strategies for pesticides.
Anniston, Alabama has a long history of operation of foundries and other heavy industry. We assessed the extent of heavy metal contamination in soils by determining the concentrations of 11 heavy metals (Pb, As, Cd, Cr, Co, Cu, Mn, Hg, Ni, V, Zn) based on 2,046 soil samples collected from 595 industrial and residential sites. Principal Component Analysis (PCA) was adopted to characterize the distribution of heavy metals in soil in this region. In addition, a geostatistical technique (kriging) was used to create regional distribution maps for the interpolation of non-point sources of heavy metal contamination using geographical information system (GIS) techniques. There were significant differences found between sampling zones in the concentrations of heavy metals, with the exception of the levels of Ni. Three main components explaining the heavy metal variability in soils were identified. The results suggest that Pb, Cd, Cu and Zn were associated with anthropogenic activities, such as the operations of some foundries and major railroads, which released these heavy metals, whereas the presence of Co and Mn, and V were controlled by natural sources, such as soil texture and pedogenesis, and soil hydrology. In general terms, the soil levels of heavy metals analyzed in this study were higher than those reported in previous studies in other industrial and residential communities.
A large and increasing volume of wastewater is produced globally by the winery and distillery industries. These wastewaters are generally acidic, high in chemical oxygen demand (COD) and color, and may contain phenolic compounds that can inhibit biological treatment systems. Treatment of distillery and phenolic compound–rich wastewaters by physicochemical, aerobic biological systems and hybrid treatment methods are discussed, as well as products derived from fungal treatment. White-rot fungi have been shown to exhibit unique biodegradation capabilities, primarily due to their production of extracellular and broad substrate range enzymes that are capable of mineralizing lignin, a recalcitrant biopolymer. One of these enzymes, laccase, catalyses the oxidation of various organic compounds with the subsequent reduction of molecular oxygen to water. Laccase synthesis, induction, and inhibition are discussed with the utilization of waste residues for laccase production and the enzyme's potential industrial applications. Distillery wastewaters offer a unique, presterilized, potential growth substrate for the production of lignolytic enzymes such as laccase. Compounds may be utilized for enzyme and biomass production resulting in remediation by the growing fungus.
This study attempted to determine the effects of heavy metals on the photosynthetic blue-green algae for their potential to use as a biosensor. The bioaccumulation of metals and its effects on pigments of Nostoc muscorum and Synechococcus PCC 7942 were assessed. The culture was grown in BG 11 liquid medium supplied with different metals like mercury (Hg), lead (Pb), and cadmium (Cd) and incubated (µM 20 concentrations) for 10 days under optimal conditions. The accumulated amounts of metals were determined by atomic absorption spectroscopy (AAS). The stress effects on photosynthetic pigment chlorophyll a (Chl a) were monitored by laser-induced fluorescence (LIF). Bio-concentration factor (BCF) reached a peak in cells on the 2nd day of incubation followed by a gradual reduction. The highest reduction in the pigment concentrations (Chl a and β carotene) was observed at 20 µM L Hg treatment. The results indicate that, cyanobacteria may serve as both potential species to be used as a biosensor and used to clean up heavy metals from contaminated water. These changes were analyzed with the long-term goal of exploiting cyanobacterial cells as biosensors.
Mountain meadows near Leadville, CO, were contaminated with trace metals through the deposition of hydraulically transported mine tailings in the early 1900s. A study was conducted to: (I) characterize the physical and chemical properties of contaminated soils, (II) determine the soil depth distribution of total, organically bound, oxide-bound, exchangeable, and water-soluble metals, and (III) evaluate trace metals in forages grown in contaminated meadows. One uncontaminated and four contaminated locations in a north-south transect were studied. Total soil metals ranged from: Cu, 14 to 1200 mg kg[sup [minus]1]; Cd, 3 to 110 mg kg[sup [minus]1]; Pb, 46 to 49000 mg kg[sup [minus]1]; and Zn, 44 to 12000 mg kg[sup [minus]1]. The greatest concentrations of total metals were found either in the surface horizons or in hydraulically deposited sand layers that were buried at three locations. Copper was predominantly associated with the organic fraction at four of the five locations, while Cd, Pb, and Zn were mainly bound to Fe and Mn oxides at all locations. The concentrations of Cd, Pb, and Zn in forages were significantly related to various fractions of soil metals and were found to be potentially detrimental to livestock health and plant growth.
In this study, for the first time the potential use of dried Vibrio parahaemolyticus PG02 to remove mercury from synthetic effluent was investigated by considering equilibrium, kinetic, and thermodynamic aspects. The results indicated that Hg2+ biosorption was best described by the pseudo-second order model. In addition, it was found that intraparticle diffusion was not the sole rate-limiting step. The ion-exchange mechanism was a predominant biosorption mechanism in the first 15 min of contact. The Langmuir isotherm better described the equilibrium data of Hg2+ biosorption than the Freundlich isotherm. According to this model, the maximum biosorption capacity was found to be 9.63 × 10−4 mol g−1 at optimum conditions (pH = 6.0 and temperature =35 °C).
Lead (Pb) is non-bioessential, persistent and hazardous heavy metal pollutant of environmental concern. Bioremediation has become a potential alternative to the existing technologies for the removal and/or recovery of toxic lead from waste waters before releasing it into natural water bodies for environmental safety. To our best knowledge, this is a first review presenting different mechanisms employed by lead resistant bacteria to resist high levels of lead and their applications in cost effective and eco-friendly ways of lead bioremediation and biomonitoring. Various lead resistant mechanisms employed by lead resistant bacteria includes efflux mechanism, extracellular sequestration, biosorption, precipitation, alteration in cell morphology, enhanced siderophore production and intracellular lead bioaccumulation.
![Anthropogenic sources of pollution [59]](https://www.researchgate.net/profile/Roopali-Roychowdhury/publication/331431332/figure/fig1/AS:731877484793856@1551504598295/Anthropogenic-sources-of-pollution-59_Q320.jpg)
![Toxicity level of different metals and non-metals The risk of superficial and groundwater contamination also is influenced by soil metal contamination. Leaching process of top soil and subsurface contamination of water, leads to further contamination of potable water. Proper knowledge of environmental basic chemistry, and related health effects of these heavy metals is necessary in understanding their speciation, bioavailability, and remedial options. The destiny and mobility of heavy metals in soil depends crucially on the chemical form and the speculation of the metal. Once in the soil, Heavy metals are adsorbed initially as a fast reaction, once they reach the soil, however, later they undergo slow adsorption reactions tending to days or years and are, therefore, redistributed into different chemical forms with varying bioavailability, mobility, and toxicity [19,20]. The distribution is controlled by certain reactions of heavy metals in soils such as: (i) mineral precipitation and dissolution, (ii) ion exchange, adsorption, and desorption, (iii) aqueous complexation, (iv) biological immobilization and mobilization, and (v) plant uptake [21]. Figure 3 denotes the redistribution of metal contaminants in the environment. Metal distribution in environment gains access to natural surroundings such as soil, water and air leading to increase in hazards of metal poisoning. Food chain contamination leads to chronic diseases in animals and human beings. Some of which can be fatal. Heavy metal poisoning, causing life threats, can occur due to industrial exposure, air or water pollution, coated food containers, processed foods packets, medicines or due to the accidental ingestion of lead-based paints. Heavy metal toxicity can lead to disruption of the central nervous system, cardiovascular system, liver, endocrine glands, gastrointestinal system, lungs, kidneys or may prove to be fatal.](https://www.researchgate.net/profile/Roopali-Roychowdhury/publication/331431332/figure/fig2/AS:731877484802048@1551504598313/Toxicity-level-of-different-metals-and-non-metals-The-risk-of-superficial-and-groundwater_Q320.jpg)
![Redistribution of metal contaminants in the environment [60]](https://www.researchgate.net/profile/Roopali-Roychowdhury/publication/331431332/figure/fig3/AS:731877484793857@1551504598335/Redistribution-of-metal-contaminants-in-the-environment-60_Q320.jpg)
![Examples of waste and their possible bioremediation strategies adapted from Brar, S 2006 [38]](https://www.researchgate.net/profile/Roopali-Roychowdhury/publication/331431332/figure/fig4/AS:731877484810241@1551504598384/Examples-of-waste-and-their-possible-bioremediation-strategies-adapted-from-Brar-S-2006_Q320.jpg)
